To limit the size of roads and highways as well as the pollution generated by road transport, it is increasingly desired to expand the rail transportation of semi-trailers on specific wagons, and to transport them over long distances by rail rather than via the road network.
For this, semi-trailers must now be loaded and unloaded using different techniques in combined road and rail terminals specially equipped for performing such operations. Special and expensive infrastructure must be provided on railway platforms for the loading and unloading of these semi-trailers.
In addition, the trains used for such transportation are also very specific. They consist of specialized wagons for transporting this type of load and, in addition, must open so as to allow the loading and unloading of semi-trailers. These wagons are complex and also very expensive.
Various opening systems are known for these specialized wagons. One possible technique is to use wagons consisting of a rolling base and a bearing railway structure capable of being separated from its rolling base by pivoting; this pivoting can be central or can take place at one of its extremities.
Central pivoting provides the possibility of access or removal at one or other of the extremities, whereas pivoting around one of the extremities only leaves one end free for the entrance and exiting of semi-trailers before and after their transportation.
Other opening methods are also possible, such as—for example—sideways movement of the bearing railway structure.
All these systems have the disadvantage of being complex and expensive.
The specialized wagons have to be motorized and must be able to provide the energy required for their opening and closing movement while their bearing structure is loaded with semi-trailers. In addition, these specialized wagons must be equipped with additional specific trackside installations in specialized stations for the loading and unloading of semi-trailers.
All these necessary investments in wagons and trackside infrastructure explain the slow development of use of rail transport for semi-trailers, notwithstanding its desirability from the social, ecological, economic and political viewpoints.
Some systems of loading and unloading semi-trailers on to and from a wagon for rail transportation are already known.
First of all, there is U.S. Pat. No. 4,425,064 in the name of WALDA, concerning a turntable borne by the wagon and accommodating a semi-trailer's wheel assembly, and its securing to a mounting bearing a hitch.
This turntable pivots between a rolling position in which it is positioned within the longitudinal axis of the wagon, and a loading/unloading position in which it is rotated in relation to the wagon.
Towards the front, the wagon also comprises a platform bearing an articulated assembly composed of oblique arms articulated on the extremities, on which there is a semi-trailer hitch supporting the front of a semi-trailer by its kingpin. The articulated arms are conrods of which the inclination allows the hitch to change from a low resting position to a raised position for supporting the semi-trailer by its front section during its railway transportation.
While this invention does indeed include a pivoting bearing structure on the wagon, intended to accommodate the semi-trailer's wheel assembly, the hitch articulated on the elevation assembly is not detachable as for the present invention and, therefore, cannot be manipulated by a handling plant, and is not usable placed on the semi-trailer in view of adjustment and its installation on the wagon.
There is also the invention described in European patent EP no. 1712444 in the name of ARBEL FAUVET RAIL.
According to this patent, the semi-trailer is loaded into a load-bearing nacelle 4, and it is immobilized on it laterally by means of fastening systems 24 and 25 and, at the front, by means of the restraining system 6 of the coupling 7. The load-bearing nacelle 4 bears upon and is affixed to the long beams of the longitudinal edges of a wagon of the type referred to as a ‘pocket wagon’.
The clamping system 6 of the coupling 7 is combined into a supporting system 1 that is detachable from the nacelle 4 via a longitudinal sliding movement at the end of its deck. This supporting system 1 comprises a hitch secured at the top, which interoperates with the semi-trailer's kingpin.
To be operational, the supporting system 1 has to be assembled at the front end of the nacelle. A controlling system allows one to adjust the hitch heightwise.
However, only the supporting system is removable with a simple longitudinal separating movement, and one can only adjust the height of the hitch when this supporting system is in place, which seriously complicates the operations of positioning and supporting the front of the semi-trailer, and of loading it on to and unloading it from the wagon.
Lastly, through the publication DE 3234375 in the name of WAGGON FABRIK TALBOT, another system is known for loading and unloading a semi-trailer on to or from a wagon of type ‘pocket wagon’ type. This system includes a tipping and pivoting platform that accommodates the semi-trailer's wheel assembly and immobilizes it through controlled sinking within the wagon. The semi-trailer's kingpin is engaged within an elevation assembly allowing one to lift the front of the semi-trailer so that it can be supported by a support platform. The elevation assembly comprises the equivalent of a hitch, but it is not detachable and is not used for positioning the semi-trailer on the wagon by means of a handling plant.
All the difficulties of manoeuvring the semi-trailer are experienced at the moment of and during its positioning on the wagon and its removal from it.